Re: Difference in behavior between HTML label and aria-labelledby

Hi Karl,

On Wed, Apr 23, 2014 at 3:00 AM, Karl Groves <kgroves@paciellogroup.com> wrote:

<snip>

> The fourth example uses a label[for] and aria-describedby.  JAWS and VO
> behave differently, from what I can tell. JAWS behaves as according top ARIA
> spec[1] but VO does not.
> 
> This raises a few questions for me.  First, for those who may also be
> inclined to test the URL above: are your results similar.


Safari 7.0.3 exposes the two hidden divs, Bat and Baz, in the AXHelp
attribute, which I believe is as per the spec for @aria-describedby
[1].

With its default settings, VO will speak the AXHelp text after a short
delay. The delay can be reduced to practically nothing, at which point
VO's behaviour is much like JAWS' in IE or NVDA's in FF, even if IE
doesn't expose the @aria-describedby values in MSAA accDescription
while FF does.


> Second, and more importantly, why the difference between the behavior of
> label[for] and aria-labelledby?  The ARIA spec says "Skip hidden elements
> unless the author specifies to use them via an aria-labelledby or
> aria-describedby being used in the current computation."   If the definition
> of "hidden" says "Indicates that the element is not visible or perceivable
> to any user. "  and "Authors are reminded that visibility:hidden and
> display:none apply to all CSS media types; therefore, use of either will
> hide the content from assistive technologies that access the DOM through a
> rendering engine."
> 
> If that's the case, why allow an exception when authors use 'aria-labeledby'
> and 'aria-describedby'?  Further, why the difference in behavior from how
> the label element behaves?
> 
> Last, how will the proposed labelfor behave?
> 

All good questions. I've no answer, but wonder if the difference in
bevaviour with @aria-labelledby and @aria-describedby versus
label[for] has to do with wanting to provide authors a way to provide
accessible names and descriptions without having to provide onscreen
text or text positioned offscreen? Do share any answers you get.

Jason

[1] http://www.w3.org/TR/wai-aria-implementation/#mapping_state-property_table


Jason Kiss
jason@accessibleculture.org
http://www.accessibleculture.org